usb: xhci: plat: Create both HCDs before adding them

As xhci_hcd is now allocated by usb_create_hcd(), we don't
need to add the primary HCD before creating the shared HCD.

Creating the shared HCD before adding the primary HCD is particularly
useful for the OTG use case so that we know at the OTG core if
the HCD is in single configuration or dual (primary + shared)
configuration.

Signed-off-by: Roger Quadros <rogerq@ti.com>
[Mathias: rearranged to fit on top of the Marvell Armada 385 phy changes]
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>